This research project concerning the study of the precursor of one of the major proteic component of tissue amyloid - the serum amyloid A (SAA) aimed primarily to the determination of the significance of the rise of SAA in patients with neoplastic diseases and to the study of its site of origin, biologic role and metabolic turnover. These goals were in part fulfilled in the first year of investigation. With a radio-immunoassay we established in 62 patients with leukemias and lymphomas and 559 patients with solid malignant tumors that SAA level was significantly elevated in patients with acute and chronic myelocytic leukemias, those with stage III and IV lymphomas and 97% of patients with solid tumors and distant metastases while it was under 400 ng/ml in all other patients but 20 with solid tumors and only localized or regional disease. In this latter group 16 patients had a rise of the SAA level rise preceeding by 40 to 214 days the appearance of distant metastases. We also found an inverse proportional correlation between the SAA level and the percentage of EAC rosette forming lymphocytes in patients with neoplastic diseases. Finally we discovered significant amounts of AA antigenically related material only in polymorphonucleated leukocytes among the circulating blood cells and we established that it was released in their culture medium between the 16th and 30th hour of culture only in 25% of the cases studied in conditions that have to be better defined. The above experiments will be continued in the second year of investigation with the study of the synthesis of SAA by polymorphonucleated leukocytes, that of the SAA effect on the helper and suppressor function of T lymphocytes and the determination of the value of SAA level as a biochemical marker of cancer dissemination in comparison with other known biochemical markers.